Comparison of various sampling methods for PCDDs and PCDFs in stack gas

There have been discussions about how complete PCDDs and PCDFs are sampled from stack gas of waste combustion plants by various sampling methods. In Germany, at present, a sampling method is used, which was first proposed by Nottrodt et al.¹, consisting of a filter device, condenser, and an absorption train. Since this sampling procedure complicates sampling and analysis, we compared this “standard procedure” with a “dilution method”, where only a filter, impregnated with paraffin, is used as trapping device, and also tested the effectiveness of XAD-2 as an adsorption trap.

As standard procedure the standard train was always used in parallel to other sampling methods. The results of four parallel sampling periods confirmed, that comparable results are obtained, when parallel sampling is carried out with the standard train.

The result of our investigation can be summarized as follows: The total emission of PCDDs and PCDFs determined by different sampling procedures varies only insignificantly. This means that sampling and analysis for PCDDs and PCDFs in stack gas could be simplified considerably.     

Comparison of variability in dioxin and furan data acquired using single train and simultaneous multiple train stack sampling methods

The variance of polychlorinated dibenzo-p-dioxin (PCDD; dioxin) and polychlorinated dibenzofuran (PCDF; furan) data obtained from single- and simultaneous multiple train methods was compared. Single train triplicate data were used from 4 stack tests obtained from a long dry kiln cement plant and 18 stack tests from a municipal solid waste (MSW) incinerator. Data from the American Society of Mechanical Engineers (ASME) report Reference Method Accuracy and Precision (ReMAP) (Lanier and Hendrix, 2001) were used for the simultaneous multiple samples, which accounted for 27 data points. Nineteen data points were acquired from an ASME research facility, 5 from a MSW incinerator unrelated to the single train MSW incinerator, and 3 from a lightweight aggregate kiln (LWAK). The ReMAP procedure was used to determine the relationship between the standard deviation and the concentration of the single train and simultaneous multiple train data. Results indicated that there was benefit from the use of simultaneous multiple train sampling for concentrations above 129 pg toxic equivalency (TEQ)/m³. There was no indication of benefit from the use of simultaneous multiple train sampling at concentrations below 129 pg TEQ/m³.

Implications:Precision of stack sampling data can be the difference between meeting and failing compliance limits. Generally, three dioxin/furan samples are acquired when stack sampling to meet compliance regulations. A reliable estimation of the data’s true concentration is not possible with this small amount of data. Increasing the precision decreases the chance that the acquired concentration deviates greatly from the true concentration. Facilities that use the appropriate stack sampling method will benefit by either improved data precision or minimal stack sampling expenses. The observations made suggest that facilities that are expected to have dioxin/furan concentrations above 129 pg TEQ/m³ would increase the precision of samples by using simultaneous multiple train sampling.     

Dioxin analysis in stack emissions, slags and the wash water circuit during high-temperature incineration of chlorine-containing industrial wastes; Part 2

PCB's and polychlorobenzene sumps have been incinerated in a high-temperature installation. The working conditions, wastes, sampling methods and analysis of the stack emissions, slag and wash water are described. No 2,3,7,8-TCDD and only ppt-traces of some PCDD congeners were detected in the stack emission. The performance criteria of the incinerator and the more important sampling procedures are discussed.     

Evaluation of the emission characteristics of PCDD/Fs from electric arc furnaces

Distribution of PCDD/F (polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran) congeners at two electric arc furnaces (EAFs) in Taiwan is evaluated via intensive stack sampling and analysis. Two kinds of exhaust system in EAFs including stack system and shutter system are selected for measuring dioxin emissions. In addition, dioxin emissions during oxidation and reduction stages at EAF-A were characterized. Results indicate that the PCDD/F concentration of stack gas in EAF-A was 4.39 ng/N m³ while total Toxic Equivalent Quantity (TEQ) concentration was 0.35 ng I-TEQ/N m³. The PCDD/F concentration of stack gas in EAF-B was 2.20 ng/N m³ and the TEQ concentration was 0.14 ng I-TEQ/N m³. 1,2,3,4,6,7,8-H_pCDF, OCDD and OCDF are the major contributors of the dioxin concentrations for two EAFs investigated and the percentage of PCDD/F in particulate phase increases as the chlorination level of the PCDD/F congener increases. The results obtained on gas/particulate partitioning of PCDD/Fs in flue gases prior to the APCD in EAFs indicate that more than 90% exists in particulate phase. In EAF-A, the PCDD/F concentration during oxidation stage is slightly higher than that measured during reduction stage, including the sampling points of CO converter outlet, prior to bag filter and stack. Majority of PCDD/Fs emitted from steel-making processes exists in particulate-phase (about 60–70%) at both EAFs investigated.     

Interlaboratory sampling and analysis of PCDDS and PCDFS in emissions from urban incinerators

Three laboratories participated in a PCDD and PCDF sampling experiment on the stack of a municipal waste incinerator and six laboratories examined a fly ash sample for PCDD_S and PCDF_S in order to assess analytical precision.

The flue gas sampling results are in agreement for the three laboratories and show that the PCDD_S and PCDF_S are predominantly in the gas phase, whereas emitted particulate account for 20% of the total PCDD/PCDF concentration.     

Distribution of polybrominated diphenyl ethers (PBDEs) and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in municipal solid waste incinerators

The stack flue gases and the ashes in different units of two municipal solid waste incinerators (MSWIs) are sampled to investigate the characteristics of polybrominated diphenyl ethers (PBDEs), polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs), and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Bottom ashes (BA) exhibited much higher PBDD/F (8.11-52.2 pg TEQ/g) and PBDE contents (20.4-186 ng/g) than those of fly ashes (0.0932-2.02 pg TEQ/g and 0.332-25.5 ng/g), revealing that the PBDD/Fs and PBDEs in the feeding waste may not be completely destroyed. The PBDE concentrations/contents in the stack flue gases (26.1-109 ng/Nm³) and in the BA (20.4-186 ng/g) of the MSWIs could reach three orders higher than those in the atmosphere and reference soils. PBDE contributions to the environment from the stack flue gases or the reutilization of BA of MSWIs should not be ignored from the developing PBDE inventory.     

Particulate Emissions from Apartment House Boilers and Incinerators

The body of information presented in this paper is directed to researchers in stack testing methodology and to those concerned with reduction of emissions through equipment upgrading programs. Extensive testing was done using the U.S. Environmental Protection Agency’s Method 5 stack sampling train to obtain emission factors for existing apartment house boilers and incinerators in the City of New York. In addition to calculating emission factors, stack emission data were examined to compare results of simultaneous emission tests and to compare the dry particulate catch of the sampling train with the total particulate catch which included the impinger catch. Conclusions reached as a result of the testing were that published emission factors for boilers burning moderately high-sulfur residual oil are applicable to New York City boilers burning low-sulfur residual oil. In addition, it was found that the back half of the sampling train—the impinger section—collects a relatively constant amount of material when sampling oil-fired boilers. This may be due to absorption of S0₂ and S0₃ in the impingers and the subsequent formation of sulfuric acid. Comparison of simultaneous boiler tests indicated that the sampling train may be sensitive to variations in operating personnel, sampling conditions, and boiler operation. From tests of on-site incinerators, it was determined that previously published emission factors may be too high for well maintained and properly operated incinerators. The back half particulate catch was found to be relatively large which may have resulted from condensation of unburned organics from the burning waste material.     

Emissions of Chlorinated Organics from Two Municipal Incinerators in Ontario

In this paper the results of sampling for trace chlorinated organics at two municipal refuse incinerators in Ontario are presented. The information may be of Interest to individuals concerned with the assessment of PCDD/PCDF (polychlorinated dibenzo-p-dioxin/polychlorinated dibenzofuran) emissions from incineration of refuse and their impact on the energyfrom- waste program. PCDDs, PCDFs, PCBs (polychlorinated biphenyls), CBs (chlorobenzenes) and CPs (chlorophenols) were quantified in all process streams including refuse, ash and stack emissions. Manual sorting of refuse and collection of ash samples were carried out simultaneously with three 24-hour continuous stack sampling tests at each plant. The results suggested that the total output of PCDDs and PCDFs varied proportionately with their input at both incinerators. However, the input of PCDDs/PCDFs could not account for their total output. The chemistry of PCDDs/PCDFs in the input and output streams were different in that only heptachlorinated and octachlorinated species were present in significant quantities in the refuse while lower chlorinated species were predominant in stack emissions and ash streams. There was no correspondence between the Input of PCBs/CBs/CPs and the output of PCDDs/PCDFs. The output of PCDDs/PCDFs, however, varied Inversely with the total output of PCBs/CBs/CPs, suggesting that the latter compounds could have been partially responsible for the formation of PCDDs and PCDFs. The PCDF emissions were also affected by combustion conditions; they were higher in magnitude and consisted of predominantly tetrachlorinated and pentachlorinated species at the plant where the combustion temperatures were lower.     

Studies on sampling methods for PCDDs and PCDFs in stack emission

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in stack emission exist both as vapor and sorbed onto the surface of particles. The partition between the two phases is of a dynamic nature and changes rapidly with temperature. When monitoring stack emissions, a sampling method must be used that efficiently collects both phases as well as any condensation aerosol formed in the sampling train. In this study, the two sampling methods used in Sweden, the cooled probe polyurethane foam plug (PUFP) sampling train and the sampling train recommended by the Swedish Environmental Protection Board has been tested for particle collection ability. The results show that an aerosol filter has to be introduced after the condensor in order to collect particle bound PCDDs and PCDFs efficiently.     

Atmospheric PCDD/F and PCB levels implicated by pine (Cedrus deodara) needles at Dalian, China

Dalian is a seaside city situated in the northeastern monsoon area of China. For the first time, levels of PCDD/F and PCB congeners in pine (Cedrus deodara) needles of Dalian urban areas were investigated. Two sampling campaigns with 17 sampling points were performed in 2002. The summation of tetra- to octachlorinated PCDD/Fs and summation of 209 PCB congeners in Dalian pine needles averaged 127+/-40 ng/kg (dry) and 4389+/-1575 ng/kg (dry), respectively. Average toxic equivalence (TEQ) for PCDD/Fs and PCBs are 2.1 and 0.4 ng/kg (dry), respectively. The pine needles can differentiate spatial variation of the pollutants. The PCDD/F and PCB levels in Dalian pine needles are low or comparable with other international regions that were not impacted by evident point sources. The data can serve as a base for long-term spatial and temporal studies of PCDD/Fs and PCBs in China.     

Long-term sampling method for polychlorinated dibenzofurans (PCDFs) and dibenzo(p)dioxins (PCDDs) in flue gas of combustion facilities

A long-term sampling method for PCDF/D in emissions from combustion facilities is presented. The sampling of PCDF/D was performed over a four week period. The results are compared to results of four one-week measurements.     

Polycyclic aromatic hydrocarbon emissions from clinical waste incineration

Since the introduction of the Environmental Protection Act in the UK, there are few reports of PAH emissions from clinical waste incinerators (CWIs) operating to improved performance standards. The main aim of this study is to determine PAH emissions from a state-of-the-art CWI focusing on the effects of reactive gases and operating variables on emissions. This was carried out by collection of stack samples over three phases of operation.

At stack conditions, most PAHs are predicted to be in the vapour phase. Reactive losses of PAHs were closely correlated by rank with expected reactivities from laboratory studies. Estimates of emissions incorporating sampling losses were derived, although no correlation was found between PAH losses and the modest levels of reactive stack gases. PAH concentrations were one to two orders of magnitude lower than earlier reports from incinerators without effective air pollution control equipment (APCE). The low levels of carbon monoxide recorded were not correlated with any PAHs.

This study demonstrates the impact of efficient combustion conditions and APCE on PAH emissions from a CWI.     

Development of a Practical Source Sampling Slide Rule

Historically, use of the nomograph to calculate isokinetic sampling rates for an EPA train has been cumbersome and awkward. In sampling situations where nomograph assumptions are not applicable, e.g., pitot tube coefficient not 0.85, dry molecular weight not 29, or where the ranges available are inadequate, e.g., stack moisture content greater than 50%, orifice meter constant less than one, the sampler cannot use the nomograph and must resort to other means for isokinetic determinations. The recent introductions of slide rule type calculators have offered some relief, but they still have inadequate capabilities and in addition, are difficult to learn and time consuming to use. The only sure alternative has been the equations. However, the equations for nozzle selection and sampling rate are not readily available in useable form in the literature. They are therefore presented in this paper with explanations.     

Sampling Airborne Solids in a Duct Following a 90° Bend

Present standardized methods (ASME Power Test Code 27, Western Precipitation Bulletin 50, etc.) of stack sampling usually stress sampling under conditions of steady flow (no variation with time) in order to obtain data representative of the source emissions. On many occasions these standardized methods are applied when the velocity and/or the mass flow rate of pollutants do vary with time, thus impairing the accuracy of the sampling results. In addition, it is difficult to evaluate any inaccuracy of the sampling data. This paper classifies these two source variables into four categories and suggests basic sampling approaches for each type of source condition. Several standardized procedures are evaluated and classified according to the source conditions to which the procedure is applicable. The intent of this paper is to show the most accurate sampling approach for each source condition and thus serve as a guide when planning source sampling programs.     

Particle Size Distributions of Kraft Paper Mill Aerosols Obtained by Airborne Sampling

Size distributions of particles at several downwind points in a Kraft paper mill plume have been determined by means of airborne sampling. Size distributions from samples close to the stack were found to have a log normal frequency distribution, but significant deviations from the log normal were found farther downwind. Several possible physical mechanisms are postulated as causes for this behavior. Plume dilution with background particles appears to be the most likely mechanism. The airborne sampling system is described, and electron micrographs of sampled particles are presented.     

Determination of cadmium, zinc, copper, chromium and arsenic in crude oil cargoes

One of the sources of trace heavy metal elements in air is emission by the oil industry, either directly through stack emissions from refineries or indirectly from emissions of combustion of hydrocarbons. Emission estimates are based mainly on the trace metal content of the crude oil processed. From a literature study carried out at the beginning of the 1990s it became clear that data on the trace metal content of crudes were scarce and showed a very large scatter. For this reason a measurement programme to assess the occurrence and concentrations of a number of trace metals, i.e. Cadmium (Cd), Zinc (Zn), Copper (Cu), Chromium (Cr), and arsenic (As), in crudes which are regularly processed in the Netherlands, was set up. By drafting strict sampling protocols and by constructing a special sampling device, as many as possible of the additional contamination sources were avoided. The study suggests that sample contamination may explain a significant amount of the scatter and some of the high concentrations reported in the literature for certain metals. The measured variation in the concentrations of Cd, Zn, and Cu is thought to be due to associated water and/or sediment particles from the producing wells or that picked up during transport. The greater consistency in our measurements for Cr and As suggests that these metals are predominantly associated with the hydrocarbon matrix. Based on the results of this work, it can be concluded that emissions of Cd, Zn, Cu, Cr, and As by the oil industry in the Netherlands are most probably significantly lower than hitherto assumed.     

Performance testing of a multimetals continuous emissions monitor

A prototype instrument, designed for continuous monitoring of hazardous air pollutant metal emissions in the stack gases of waste incinerators and industrial furnaces, has undergone a performance evaluation that included a relative accuracy test audit. The test results confirmed the instrument's ability to accurately measure stack gas metal concentrations and thus validate the applicability of the candidate technique for compliance assurance monitoring for the specific source involved. The analytical accuracy of this system, documented during the recent test exercise, represents a significant improvement in performance relative to that previously achieved, and can be attributed with certainty to the recent implementation of a shrouded nozzle sampling system. By reducing deposition losses of particulate matter in the extracted stack gas stream to acceptable levels, presentation of a more representative sample stream to the elemental analyzer has been accomplished. The present paper discusses the design and operation of the multimetals continuous emissions monitor (MMCEM), the shrouded nozzle sampling system, and the results of recent performance testing.     

Calibration of polyurethane foam (PUF) disk passive air samplers for quantitative measurement of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs): factors influencing sampling rates

PUF disk passive air samplers are increasingly employed for monitoring of POPs in ambient air. In order to utilize them as quantitative sampling devices, a calibration experiment was conducted. Time integrated indoor air concentrations of PCBs and PBDEs were obtained from a low volume air sampler operated over a 50 d period alongside the PUF disk samplers in the same office microenvironment. Passive sampling rates for the fully-sheltered sampler design employed in our research were determined for the 51 PCB and 7 PBDE congeners detected in all calibration samples. These values varied from 0.57 to 1.55 m3 d(-1) for individual PCBs and from 1.1 to 1.9 m3 d(-1) for PBDEs. These values are appreciably lower than those reported elsewhere for different PUF disk sampler designs (e.g. partially sheltered) employed under different conditions (e.g. in outdoor air), and derived using different calibration experiment configurations. This suggests that sampling rates derived for a specific sampler configuration deployed under specific environmental conditions, should not be extrapolated to different sampler configurations. Furthermore, our observation of variable congener-specific sampling rates (consistent with other studies), implies that more research is required in order to understand fully the factors that influence sampling rates. Analysis of wipe samples taken from the inside of the sampler housing, revealed evidence that the housing surface scavenges particle bound PBDEs.     

Uptake rates of alkylphenols, PAHs and carbazoles in semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCIS)

Passive sampling devices provide a useful contribution to the monitoring of contaminants in the aquatic environment. However, calibration data needed for the calculation of water concentrations from sampler accumulations are restricted to a limited number of compound classes. Thus uptake of a range of alkylated phenols (AP), polycyclic aromatic hydrocarbons (PAH) and carbazoles was determined for semipermeable membrane devices (SPMDs) and polar organic chemical integrative samplers (POCIS) using a flow through exposure system. Sampling rates ranged from 0.02 to 0.26 l d(-1) for POCIS and 0.02 to 13.83 l d(-1) for SPMDs. Observed SPMD uptake was also compared to that predicted by an empirical model including the use of performance reference compounds (PRCs). Predicted sampling rates did not differ by more than a factor of 1.3 from experimental values for PAH, providing further evidence that the PRC approach can be successfully used to determine in situ sampling rates for these compounds. Experimental sampling rates for AP in SPMDs were, however, much lower than predicted. This discrepancy was too large to be explained by small uncertainties in the calibration system or in the calculations. Based on these data we conclude that while hydrophobic AP are accumulated by SPMDs their partitioning cannot be predicted from their logK(ow) using current methods. Due to this lower than expected uptake, sampling rates were only higher in SPMDs than POCIS in the range of logK(ow)>5.0. Simultaneous deployment of both sampler types allows the study of compounds with a broad range of physicochemical properties.     

Performance Testing of a Multimetals Continuous Emissions Monitor

ABSTRACT

A prototype instrument, designed for continuous monitoring of hazardous air pollutant metal emissions in the stack gases of waste incinerators and industrial furnaces, has undergone a performance evaluation that included a relative accuracy test audit. The test results confirmed the instrument's ability to accurately measure stack gas metal concentrations and thus validate the applicability of the candidate technique for compliance assurance monitoring for the specific source involved. The analytical accuracy of this system, documented during the recent test exercise, represents a significant improvement in performance relative to that previously achieved, and can be attributed with certainty to the recent implementation of a shrouded nozzle sampling system. By reducing deposition losses of particulate matter in the extracted stack gas stream to acceptable levels, presentation of a more representative sample stream to the elemental analyzer has been accomplished. The present paper discusses the design and operation of the multimetals continuous emissions monitor (MMCEM), the shrouded nozzle sampling system, and the results of recent performance testing.